Purposes of this project include (1) exploration of the prenatal origins of human postnatal dentofacial growth patterns and polymorphisms; and (2) the design of histologic criteria which would be sensitive and reliable enough to demonstrate regular and variable patterns of growth changes according to the vital statistics and familial history of the abortuses studied. Aim one will be pursued using a "developmental staging" scheme for dentition, facial primordia, craniofacial bones as seen in serial histologic sections of over 685 human abortuses representing the key time periods of craniofacial development. Intra- and inter-individual data will be reduced and analyzed on an information background of the abortus which includes sex, race, chromosome information (when practical), age and available histories of the pregnancy and family. Aim number two is intended to show the regular variations in age-typical growth stages. Data on tooth morphogenesis, organ and skeletal development, for example, will be handled using correlation matrices similar to those used for postnatal studies. These interorgan-inter-regional correlation matrices have the capacity to retrospectively explain, in part, why specific organs and/or system cluster in birth defect syndromes, e.g., orofaciodigital. Moreover, encoded background histories on the pregnancy and available karyotypes, for example, can help explain defects as either isolated or familial events.